The wireless cellular communications network has grown exponentially over the years. A Long-Term Evolution (LTE) system offers high peak data rates, low latency, improved system capacity, and low operating cost resulting from simplified network architecture. LTE systems, also known as the 4G system, also provide seamless integration to older wireless network, such as GSM, CDMA and Universal Mobile Telecommunication System (UMTS). The 3rd generation partner project (3GPP) network normally includes a hybrid of 2G/3G/4G systems. With the optimization of the network design, many improvements have developed over various standards, especially in providing wireless IP services via an Evolved Packet System (EPS).
The EPS/IP bearer and connection management and allocation functionality can be provided towards the applications and the terminal devices using an Application Programming interface (API). For external applications, the EPS/IP bearer and connection management and allocation functionality may be provided through an AT command API in accordance with 3GPP TS 27.007 “AT command set for User Equipment (UE)”. AT commands are used for controlling Mobile Termination (MT) functions and GSM/UMTS network services from a Terminal Equipment (TE) through Terminal Adaptor (TA).
3GPP introduces multiple timers to solve network congestion problem. For example, when a session management or EPS session management (SM/ESM) request is rejected by the network, the network may trigger a session management timer for APN based congestion control. Before the timer expiry, any further SM/ESM request triggered by the TE side will always fail because such request is barred by the network. However, the TE does not understand this barring situation and it keeps trying. Such blind retrying cause heavy power consumption since the retry will not succeed until the barring is canceled upon timer expiry and the TE cannot enter sleep mode. In the current standard, the TE has no formal way to know how long each APN is barred by the network due to network congestion.
A solution is sought for controlling backoff timer via the use of AT commands for responding barring status to the TE. It can reduce wasteful retries to save power consumption.